Process for the manufacture of ethyl chloride



Allg. 9, 1966 D M HURT PROCESS vFOR THE MANUFAOTURE OF ETHYL CHLORIDE Filed June 26, 1963 high conversion.

Filed June 26, 1963, Ser. No. 290,799 3 Claims. (Cl.l 26o- 663) This invention is directed to an improved lprocess for v the manufacture of ethyly chloride. More particularly, this invention is directed to an improved process for the manufacture of ethyl chloride wherein provision is made for removing catalyst poisons from the reaction system.

It has been known that ethylene will react with hydrogen chloride in aliquid reaction medium in the presence of'Friedel-Crafts type catalysts such as anhydrous ferric chloride, aluminum chloride yor zinc chloride. It is also known that these catalysts cause polymerization of the ethylene-in the reaction mass to higher molecular weight materials and that these higher `molecular weight materails act as catalyst poisons causing the catalyst to lose its activity. Higher olefins such as isobutylene are much more prone to polymerize than ethylene. It is further known that ferrie chloride causes less ethylene polym- `erization than the aluminum chloride or zinc chloride catalysts. v l 3 The usual method for overcoming the diticulty of the catalyst poisoning caused by the polymerization of i chloride to ethyl chloride.

It is, therefore, an object of this invention to provide an improved process for preparing ethyl chloride from ethylene and hydrogen chlorid.

It is another object of this invention to provide an improved process for preparing ethyl chloride from ethylene and hydrogen chloride which overcomes the problem of catalyst poisoning inherent in the art processes.

It is a further object to provide an improved process for preparing ethyl chloride from ethylene and hydrogen chloride which operates in a continuous manner at 'These and other objects will become apparent from the following description and claims. L

More specifically, the present invention is directed to -a novel, improved process for the preparation of ethyl Vethyl chloride vapors recycled from the reaction zone in a gas-liquid contactor, therein allowing ethyl chloride and from 0.1 mole to 20 moles per 100 moles of ethyl chloride, of other constitutents having boiling points less than 150 C. to vaporize at one atmosphere` from said liquid portion, collecting said vaporized materials of said "portion ofthe reaction medium and returning the vaporized materials to said reaction zone and removing the un- United States Patent O 3,265,748 Patented August 9, 1966 ICC ' improvement consists in causing hydrogen chloride to reflux and returned to the reaction zone.

react with ethylene in the presence of anhydrous ferric chloride suspended and dissolved in liquid ethyl chloride which may contain varying amounts of higher molecular weight organic compounds. It is known that liquid ethyl chloride can be used as the reaction medium in this process although higher boiling halogenated aliphatic hydrocarbons are usually preferred in the art process. In a convenient form and the form usually used, the reaction is carried out in a reaction zone consisting of a reaction vessel, a fractionation or rectification column and a reflux condenser. Gaseous ethylene and hydrogennchloride are passed into the liquid medium containing the suspended catalyst. A vapor mixture of ethyl chloride, hydrogen chloride, ethylene and by-products Tpasses into the fractionation column and condenser.

Some of the ethyl chloride and all of the by-products are condensed in contact with the descending ethyl chloride Most of the unreacted ethylene and hydrogen chloride are not condensed but are removed from the condenser system along with small amounts of ethyl chloride and returned to the reaction zone as an externaltrecycle. Product ethyl chloride is removed from the condenser system as a liquid. Sumcient ethyl chloride is returned to the reaction zone to maintain proper descending reflux in the column and to maintain the liquid level in the reaction zone at the desired level. t

As the reaction continues, the polymeric 'by-products which form collect in the liquid reaction medium and poison the catalyst. Since these polymerization products arevrelatively non-volatile compared to the ethyl chloride reaction medium, they cannot be removed by vaporization. Conversion of ethylene and hydrogen chloride to ethyl chloride decreases rapidly with time due to catalyst poisoning. Addition of fresh catalyst, as taught bythe art, partially overcomes this problem but this soon fails too since the amount of catalyst poison soon builds up to a point where catalyst is deactivated as soon as it is added.

It has now been found that the polymerization byproducts vary from relatively low boiling materials having boiling points of about 56 to very high 4boiling materials having boiling points greater than 225 C. Nondistillable tars also occur. In a qualitative way it has been found that these lay-products having boiling points below 150 C. at one atmosphere are relatively inocuous catalyst poisons. Those having boiling points above 150 C. and particularly those boiling above 170 C. are very severe ferrie chloride catalyst poisons however. This was demonstrated by fractionally distilling a sample of the polymeric by-product, then agtating one partof each fraction with tive parts of the ferrie chloride catalyst and parts of ethyl chloride for two hours. The solid iron compounds were then isolated and analyzed for ferrous chloride. Those samples of iron compounds treated with by-products having boiling points less than C. contained about 11% ferrous chloride, whereas those treated with by-products having boiling points between 150 and 170 C. contained about 13% ferrous chloride while thoseI treated with 'by-products boiling above C. contained from 21% to 35% ferrous chloride. This also shows that catalyst deactivation or poisoning is due, in part atleast, to reduction of ferrie chloride to ferrous chloride. Physical adsorption of high molecular weight materials on the catalyst .surface also accounts for some of the catalyst poisoning.' Judging from those by-products identified, they seem to consist of four types of compounds; i.e., alkanes such asA 3- lfrom the reaction mass.

methyloctane, oletines such'as dimethylhexene and trimethylpentene, chloroalkanes such as 2-chlorobutane and chlorinated olefines such as chloropentene and chloroheptene. This list is far from complete, since it is known that at least 29 different by-products are formed.

It has been further found that as little as 1% of the ethylene polymerization lay-products in the ethyl chloride reaction mass having boiling points of 170 C. and above cause severe deactivation of the ferrie chloride catalyst. It has also been found that of the four types of by-products formed as mentioned heretofore, the olenes are the worst catalyst poisons. The chlorinated alkanes are relatively harmless as might be expected since they are used as solvents for this process in some cases. It has also been found that polymerization increases markedly as the catalyst becomes deactivated.

The present process overcomes the problem of catalyst poisoning and diminished conversions due to polymerization 'by-products by continuously removing these byproducts from the reaction mass. This is accomplished by continuously removing a stream of the liquid ethyl chloride reaction mass from the reaction zone and treating this stream in a gas-liquid contactor with a mixture of 'superheated ethylene, hydrogen chloride andfethyl chloride vapors recycled from the reaction zone. -The super heated vapors contact the stream of liquid ethylene chloride reactionvmass at a temperature suicient to cause ethyl chloride and a portion of the byproductsto vaporize The vaporized material, which of course includes the ethylene, hydrogen chloride and lethyl chloride injected as superheated vapors, is returned to the reaction zone, most convenlently by injecting it into the reaction vessel or fractionation column. The'nonvaporized portion of the stream, containing the high boiling constituents which act as catalyst poisons, is removed for disposal such as burning. This portion contains any ferrie chloride catalyst which was dissolved or suspended in the original reaction mass stream. For this reason it is necessary to continuously add fresh ferrie vchloride catalyst to the reaction mass to replace that removed. Using this method of operation, it has been found that it is possible to carry out the reaction of ethylene with hydrogen chloride in a continuous manner in high conversion and yield essentially without interruption.

The present invention will be better understood by reference to the accompanying drawing which illustrates a representative and preferred embodiment of the improved process of this invention. In the drawing, the reaction system shown consists of an ethylene source 10, an ethylene ow meter 11 for measuring and controlling the ethylene flow, a hydrogen chloride source 12, a hydrogen chloride flow meter 13 for measuring and controlling the flow of hydrogen chloride, a feed ow meter 14 for measuring and controlling the flow of the mixed gases, a feed inlet 15 and catalyst addition line 17 which feed directly into the liquid ethyl chloride-ferrie chloride reaction mass 18 which is contained in the reaction vessel 16. Attached tolreaction vessel 16 and forminga part thereof is fractionation column 19 which, in turn, communicates with vapor line 20, condenser 21, liquid-vapor separator 22, liquid return line 23, liquid reux returnl line 24, and a crude product take-off line 25. The crude product take-off line communicates with a fractionation column 43, reboiler 46, an ethyl chloride product line 44, reflux condenser 45, and a vapor return line 26. From the top of separator 22, vapor line 27 leads to vent valve 28, compressor 29, recycle line 30, recycle vapor llow meter 32, and vapor take-off line 31. Vapor takeoff line 31 leads to the bottom of gas-liquid contactor 33 via control valve 34, ow meter and heat exchanger 36.` Line 37, containing a ow meter 38, connects the 'bottom of reaction vessel 16 with the top of gas-liquid contactor 33. Vapor line 39 connects the top of gasliquid contactor 33 with the reaction vessel 16. Liquid 4 line 40 and valve 41 are connected to the bottom of contactor 33. Line 42 connects the outllow of the heat exchanger with the gas-liquid contactor 33.

In operation, recycle vapors from line 30, consisting mainly of hydrogen chloride with smaller amounts of ethylene and ethyl chloride, are measured by vflow meter 32. This mixture is then combined with approximately equivalent amounts of ethylene and hydrogen chloride feed from sources 10 and 12, measured and controlled by meters 11 and 13, and the resulting mixture, at the desired ow rates, as measured by meter 14, enters reaction vessel 16 via inlet 15. The reaction vessel 16 contains a reaction medium 18 consisting of a suspension and/or solution of anhydrous ferr-ic chloride in ethyl chloride.

Ethylene and hydrogen chloride react, in part, in reaction ride and lay-products into lthe fractionation column 19 where fractionation occurs in contact with descending liquid rellux from line 24 which condense the by-products and return them to the reaction vessel 16. Vapors from the top of 19 pass into vapor line 20, hence into coudenser 21. In condenser 21 most of the ethyl chloride is condensed and descends into the vapor-liqu-id separator 22 along with the uncondensed materials. The separated liquid condensate is returned to the fractionation column 19 via lines 23 and 24. Sufficient liquid is returned to the fractionation column 19 to maintain proper descending reux for fractionation in the column 19 and to mainytain Ithe proper liquid level in the reactor. The remainjing liquid, being crude ethyl chloride, is removed via line 25 to a fractionation column 43 wherein pure ethyl chloride tis obtained and drawn off the column from the reboiler 46 via product line 44. Any dissolved hydrogen chloride and ethylene in the crude ethyl chloride are collccted inthe reflux condenser 45 and returned to the reaction system via line 26. The uncondensed vapors from the separator 22 pass into line 27, drawn by the compressor 29. Valve 28 is merely used to vent-off excessive pressure in the system. The compressor 29 acts to provide suicient pressure to cause the vapors to flow. A portion of the vapors leaving compressor 29 pass via recycle line 30 and measuring means 32 into the reaction vessel 16 as heretofore described. The other portion of the vapors leaving compressor 29 pass via line 31, control valve 34 and flow meter 35 into heat exchanger 36 where the vapors are superheated considerably above ltheir dew point. The superheated vapors then pass via line 42 into the bottom of the gas-liquid contactor 33.

Part of the liquid ethyl chloride reaction mass 18 is passed via line 37 and control meter 38 into the top of gasliquid contactor 33. Contact of the superheated vapors from line 42 with the liquid from line 37 causes a portion of the liquid to vaporize as indicated hereinbefore. These vapors pass via line 39 into reaction vessel 16 for return to the reaction mass. The unvaporized portion passes from the gas-liquid contactor 33 via line 40 and valve 41 lto Waste. Usually the Waste is burned. Concurrently with the above, fresh catalyst is added to reactor 16 via catalyst feed line 17 in sufficient quantity to replace that removed via line 37.

The above described method does not depend on any particular size system or reaction mass. The reaction system is designed, of course, to meet the requirements of the size of reaction mass or production rate contemplated. The reaction temperatures and pressures used in this invention are those disclosed and used in lthe art. Flow rates are chosen to give the desired reaction mass Kand to t the size of the reaction equipment. The rate of removal of reaction mass to the gas-liquid contactor 33 is somewhat variable, usually from about 0.1% to 10% of the reaction mass is transferred to the gas-liquid contactor 33 each hour. The temperature of the superheated vapors depends primarily on the react-ion pressure. In a representative commercial scale operation, ref' action vessel 16 was a 13,610 gallon pressure vessel. and

the. fractionation column 19 was a 5 ft. x 17 ft. column lled'with 15 sieve trays. Thel reaction vessel contained at start-up approximately 25,000 lbs. of ethyl chloride reaction solvent `contain-ing 1% ferric chloride catalyst. The reaction` .temperature was varied from` 25 to 70' C.

with corresponding variations in reaction pressure of from 160 to 200 p.s.=i.g. The reaction temperature of 65 C. and the reaction pressure of 1851 p.s.i.g. are usually preferred.

The feed stock enters the reactor 16v via iinlet 15, con- .sisting of to 25 mole percent of each of ethylene and the desired rate. The added ethylene and' hydrogen chloride feed, entering. via` lines 10 and 12 and:` consisting of approximately. equivalent amounts of the two reactants, varied fromr 4600 to 14,000 lbs/hr. The preferred total feed rate, measured at ow meter 14, is 120,000 lbs/hr. The recycle vapors flow rate varied fromI 300 tot: 1400 cubic feet per minute (26,000 to 122,000 lbs/hr.) with 1200 cubic feet per minute (106,000 lbs/hr.)` being the preferred recycle` vapor ow rate. The recycle vapors contained from 55% to 83% hydrogen chloride, 2% to 20% ethylene and 15% to` 25% ethyl chloride. The preferred make-up of the recycle` vapors being 75% hydrogen` chloride, 5% ethylene and 20% ethyl chloride.

During the react-ion from: 1000 to 2500 lbsi/hr. of the reactionwmixture, at to- 75 C., were reino 'ed'from the reaction mixture and were .passed into the: gas-liquid contactor 33' with 2000 lbs/hr; corresponding` tothe preferred rate of removal. The gas-liquid contactor 33t-was la 20 inch x 7 ft. 4'4 inch sieve: tray contactorv of 132 gallon capacity. Concurrently, from 25 to 150# cubic feet-per minute of vapors inline 31, heated to from 50 to: 140

C. with` steam in heat exchanger 36, were passed into. the gas-liquid contactor 33. The ow and temperature of 'heated vapors were adjustedv to meet the requirements of the ow of liquid, the temperature and the pressure. A

flow of 149 cubic feet per minute at 140' C. corresponds to the preferred ow rate for .the superheated vapors.

lThe flow of vaporized material` from the gas-liquid contactor 33 through vline 39` to the reactor 16 varied from 25 to 100 cubic' feet per minute at from 45 -to 65 C.

The vaporized material from the gas-liquid. contactor which is returned to the reaction vessel 16 via line 391 consists of ethyl chloride, ethylene and hydrogen; chloride containing up to 0.2 weight percent of by-pro`ducts hav-l ing boiling points up: to 150 C. This ow isv of course, directly dependent on the llow of liquid` and superheated vapors into the gas-liquid contactor 33. A tow` of 95 cubic'feet per minute at 60 C. corresponds: to the pre:- ferred rate of iow for the vaporized' materials from the. gas-liquid contactor 33 back to the reaction vessel? 16.

`The flow of unvaporized material from the gas-liquid.

contactor 33 via line 401isagain dependent on the ow .of materials into the contactor 33. It varied from 300 Y fto 1200 lbs./hr. with 400 lbs/hr. cor-responding'to the preferred ow rate. These results indicatethat to 'y 48% by weight of the liquid entering. contactorl 33 rel was from 4200 to 13,900 lbs/hr. with 13,900 lbs/hr. corresponding to the preferred rate of recovery. The

conversion of hydrogen chloride varied from 90% -to v 100% and the conversion of ethylene from.90% to 100%.

The yield of ethyl chloride varied from 90%l to 99.6% with 99.6% corresponding to the preferred yield of ethyl chloride.

. When the same process was carried out as hereinbefore described without passing any liquid reaction. mass t through contactor 33 along with heated vapors from line 31, originally high conversions `were obtained` but these rapidly decreased. After only 16 hours the coni version had decreased to 75% and in 48 hours the catalyst w-as essentially dead. Additions of fresh catalyst prolonged the running time but after 60 hours even fresh catalyst had little or no effect on conversion. Thus, after 60 hours and 133,000 lbs. of production', it was necessary to shut down the reaction system and remove the entire Withthe method of this invention the l system was operated for greater than` one month contin-k.

reaction mass.

invention is not limited to the specific embodiments thereofexcept as defined in the appended claims.

The' embodiments of the.` invention in which an exclusive property or privilege is claimed are dened as follows:

1. In the process for preparing ethyl chloride comprising contacting hydrogen chloride and ethylene at a temperature from 25 C. to 75 C. in a reaction zone in the'presence of anhydrous ferrie chloride catalyst contained. in a reaction medium, said reaction medium containing ethyl` chloride as the'major constituent, and` wherein the vaporous effluent from. `the reaction zone is con densed into-a separator where the liquid is separated from the eiuent vapors, a portiony of the separated liquid thereafter being distilled to obtain the product ethyl chloride, the improvement which comprises continuously removing a portion of said liquid ethyl chloride reaction medium from said reaction zone, contacting said removed liquid portion with superheate'd vapors recycled from the reaction zone` thereby vaporizing the ethyl chloride and from` 0.1 mole to 20 moles, per 100 moles of ethyl chloride, of other constituents having boilingy points less than C. at one atmosphere from said removed liquid portion, collecting andk returning only said vaporized materials of said. liquid portion to saidL reaction zone, and replenishing the catalyst as required by adding fresh catalyst to the reaction medium.

2". In the process for preparing ethyly chloride comprising contacting hydrogen chloride and ethylene at a temperature from 25 C. to 75 C. in a reaction zone in the presence of anhydrous ferrie chloride catalyst contained in a reaction medium, said reaction medium containing ethyl chloride as the major constituent, and wherein the vaporous etliuentv from the reaction zone is condensed into a separator where the liquid is separated from the eluent vapors, a portion` of the separated liquid thereafter being distilled to obtain the produce ethyl vchloride, the improvement which comprises continuously removing a portion of said liquid ethyl chloride. reaction medium from said reaction zone, contacting said removedy liquid portion with a superheated mixture of ellluent vapors comprising ethylene, hydrogen chloride, and ethyl chloride from said. separatorA thereby vaporizing the ethyl chloride and from 0.1 mole. to 20 moles, yper 100 moles of ethyl chloride, of other constituents having` boiling points less than 150 C. at. one atmosphere from said removed liquid portion, collecting and returning only said vaporized materials of said liquid portion to said reaction zone, and replenishing the catalyst as required by adding fresh catalyst to the reaction medium.

3. In .the process fork preparing ethyl chloridel comprising contacting hydrogen chloride and ethylene at a :mperature from 25 C. ,to 75 C. in a reaction zone 1 the presence of anhydrous ferric chloride catalyst conained in a reaction medium, said reaction medium conaining ethyl chloride as a major constituent, and wherein he vaporous eiuent from the reaction zone is condensedl nto a separator where liquid is separated from the eluent 'apors, a portion of the separated liquid thereafter being listilled to obtain the'product ethyl chloride, the improvenent which comprises continuously removing a portion if said liquid ethyl chloride reaction medium from said 'eaction zone, contacting said removed liquid portion with t superheated mixture of efuent vapors comprising ethflene, hydrogen chloride, and ethyl chloride from said separator, thereby vaporizing the ethyl chloride and from 3.1 mole to 20 moles, per 100 moles of ethyl chloride, of other substituents having boiling points less than 150 C. at one atmosphere from said removed liquid portion, collecting and returning only said vaporized materials of said liquid portion to said reaction zone, disposing of the unvaporized constituents of said liquid portion,rand replenishing the catalyst as required by adding fresh catalyst to the reaction medium.

References Cited by the Examiner UNITED STATES PATENTS 2,140,927 12/1938 Pierce 260-663 2,225,933 12/1940 Slotterbeck 260-663 2,353,563 7/1944 Hemmnger 260-663 2,392,454 l/ 1946 Bond et al. 260-663 2,434,093 l/l948 Axe 260--663 2,446,124 7/1948 Boyd' 260-663 2,945,897 7/1960 Eisenlohr 260-663 LEON ZITVER, Primary Examiner.

K. V. ROCKEY, Assistant Examiner. l 

1. IN THE PROCESS FOR PREPARING ETHYL CHLORIDE COMPRISING CONTACTING HYDROGEN CHLORIDE AND ETHYLENE AT A TEMPERATURE FROM 25*C. TO 75*C. IN A REACTION ZONE IN THE PRESENCE OF ANHYDROUS FERRIC CHLORIDE CATALYST CONTAINED IN A REACTION MEDIUM, SAID REACTION MEDIUM CONTAINING ETHYL CHLORIDE AS THE MAJOR CONSTITUENT, AND WHEREIN THE VAPOROUS EFFLUENT FROM THE REACTION ZONE IS CONDENSED INTO A SEPARATOR WHERE THE LIQUID IS SEPARATED FROM THE EFFLUENT VAPORS, A PORTION OF THE SEPARATED LIQUID THEREAFTER BEING DISTILLED TO OBTAIN THE PRODUCT ETHYL CHLORIDE, THE IMPROVEMENT WHICH COMPRISES CONTINUOUSLY REMOVING A PORTION OF SAID LIQUID ETHYL CHLORIDE REACTION MEDIUM FROM SAID REACTION ZONE, CONTACTING SAID REMOVED LIQUID PORTION WITH SUPERHEATED VAPORS RECYCLED FROM THE REACTION ZONE THEREBY VAPORIZING THE ETHYL CHLORIDE AND FROM 0.1 MOLE TO 20 MOLES, PER 100 MOLES OF ETHYL CHLORIDE, OF OTHER CONSTITUENTS HAVING BOILING POINTS LESS THAN 150*C. AT ONE ATMOSPHERE FROM SAID REMOVED LIQUID PORTION, COLLECTING AND RETURNING ONLY SAID VAPORIZED MATERIALS OF SAID LIQUID PORTION TO SAID REACTION ZONE, AND REPLENISHING THE CATALYST AS REQUIRED BY ADDING FRESH CATALYST TO THE REACTION MEDIUM. 